Characteristics of Living Things

1. Characteristics of Living Things

2. Defining a living thing is a difficult task. • How would you define “living”? • What is life? • What do you need to survive? • What does a plant need? • What does a fish need?

3. A living thing possesses certain properties that help define what life is.

4. 1. Cells Amoeba - single celled organism Snail - multi-celled organism • All living things are made up of one or more cells. • The cell is the smallest functioning unit of all living things. • A living thing can be composed of one cell or many cells.

5. Cells • Cells are usually too small to be seen with the naked eye. • Cells are organized into tissues - a group of cells that perform the same function. • Tissues form organs such as the stomach and kidney. • A number of organs compose an organ system such as the digestive system. • An organism is a complex structure of organ systems. Human Heart

6. 2. Metabolism • All living things are capable of taking materials from the surroundings and using them for energy to survive. • Organisms acquire nutrition by absorption, photosynthesis or ingestion.

7. 3. Response to Stimuli • All living things are able to respond to stimuli in the environment. • Living things respond to light, heat, sound and contact with chemicals or other objects. • Organisms can detect stimuli with eyes, ears, taste buds etc.

8. 4. Growth • All organisms grow or mature over time. • During growth a living thing transforms material that is unlike itself into materials that are like it. • A human digests a meal of meat and vegetables and transforms the material into more of him/herself.

9. 5. Reproduction • All living things contain the universal genetic code and have the ability to produce copies of itself by a process called reproduction. • Bacteria grow quickly and split into two organisms by a process called asexual reproduction. • More complex organisms, like animals, engage in sexual reproduction which requires two parents that contribute genes to their offspring.

10. 6. Respiration • All living things exchange gas with the environment. • Animals inhale oxygen gas and exhale carbon dioxide gas • Plants absorb carbon dioxide from the environment and release oxygen. • Organisms perform chemical reactions during respiration.

11. 7. Homeostasis • All living things must maintain a stable internal condition no matter the environment. • Animals regulate body temperature by sweating or shivering. • Organisms perform chemical reactions and have physical properties that help to maintain homeostasis.

12. 8. Evolution • Populations of organisms have the ability to adapt to their environment through the process called evolution. • During evolution changes occur in populations, and the organisms in the population become better able to metabolize, respond and reproduce. • Organisms develop abilities to cope with their environment that their ancestors did not.